"After the War of 1812 the question was again raised...".
From The Northwest under three flags, 1635-1796:
Entering the Detroit River on the 11th of July, 1796, they discovered first a few widely scattered houses set along the low lying shores, but as they progressed they found clustered about the new British post some twenty houses in all stages of completion. The region [in Canada] was known as the district of Malden, but as yet the name of Amherstburg had not been given to the town, and for months it was known simply as the new British post and town near the island of Bois Blanc, an island by the way that was claimed to be within the United States, greatly to the disturbance of Governor Simcoe (3).
(3) The ownership of the island was not settled until after the treaty of Ghent in 1817. After the War of 1812 the question was again raised.--War Department MSS.: Protest of Colonel Anthony Butler, July 1, 1815; and Andrew J. Dallas to Colonel Butler, May 31, 1815.
Which country owned Bois Blanc after 1817? Canada.